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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Research Project #434433

Research Project: Systematics, Nomenclature, and Genetic Diversity of Priority Genera of Woody Landscape Plants

Location: Floral and Nursery Plants Research

2023 Annual Report

Objective 1: Conduct systematic and genetic analyses of priority woody landscape plant genera (chiefly Ulmus, Quercus, and Fraxinus) to elucidate their systematic relationships, revise their taxonomic classifications, and assess the amount, apportionment, and nature of the genetic diversity they contain. Record and disseminate characterization data via GRIN-Global and other data sources. Subobjective 1A – Elucidate the taxonomy and cytology of Fraxinus (ash) in eastern North America. Subobjective 1B – Determine the distribution of alleles of expressed loci in oaks (Quercus). Subobjective 1C – Clarify the taxonomy and diversity of Ulmus (elms), emphasizing potentially disease-resistant germplasm in subg. Oreoptelea. Subobjective 1D – Clarify the taxonomy and reproductive biology of Celtis. Sub-objective 1E – Carry out taxonomic research that meets the needs of stakeholders, such as the production of regional floras and botanical manuals, in collaboration with other scientists and horticulturists. Objective 2: Efficiently and effectively maintain and expand the U.S. National Arboretum Herbarium, Seed Herbarium, and associated documentation as foundational biological resources for agricultural, botanical, and plant genetic resource research. Objective 3: Determine the identity and basic biological characteristics of selected invasive woody plants in the United States.

Work will involve study of plant material, both in wild habitats and cultivated in our botanical garden. We will carry out classical studies using the morphology of the plants, flow cytometry to estimate genome size and thus ploidy level, and study of various DNA markers, including SSR markers for simple parentage studies and NextGen sequencing studies to gather detailed information on evolutionary relationships and history of plant groups. Research will also involve a wide variety of analyses, including phenetic analyses for investigating overall patterns of variation, and searching for clusters and discontinuities in the distribution of plants through multivariate character space; phylogenetic analysis for investigating ancestral relations among groups of plants; and admixture analysis for detecting hybridization.

Progress Report
This is the final report for the Project 8020-21000-080-000D which ended March 19, 2023. New NP301 OSQR-approved project 8020-21000-081-000D, entitled “Curation, Modernization, and Information Management of the U.S. National Arboretum Herbarium Collections” has been established. Substantial results were realized over the five years of the project. ARS scientists resolved the taxonomy of North American ashes (Fraxinus spp.) using morphological and cytological data, informing future management efforts. They created a phylogeny of the elm genus (Ulmus) based on genomic data to better understand its biogeography and population structure. They identified over 50 candidate genes in Fraxinus for Emerald Ash Borer resistance, which have implications for breeding and conservation. They documented the genetic diversity of hackberry (Celtis spp.) and clarified the ranges and genetic makeup of the invasive English ivy (Hedera spp.). Additionally, great strides were made in the U.S. National Arboretum Herbarium Collections, including a massive, high-throughput project to digitize the entire herbarium, resulting in digital image files and pertinent metadata for the entire 700,000-specimen collection. Upon retirement of the former Lead Scientist, attention of the Project turned solely to maintaining the herbarium collections (Objective 2) for the remainder of the project period. Though the imaging of the U.S. National Arboretum Herbarium concluded in early 2022, we continued to curate and manage the associated metadata for the collection’s specimens. Digital records for all 700,000 specimens were completed through a combination of crowdsourcing and contract work and included taxonomic name, collection event information, date, and country. All the data has been undergoing rigorous quality control to standardize the data and correct any errors. We initiated a non-assistance cooperative agreement with a company that specializes in scientific collection data to develop a collection management system that will maintain the herbaria’s digital specimen data and images, eventually allowing the collections to be accessible through a public-facing online portal. In the project period, we were able to import a subset of our data into the platform, modify certain fields to meet our unique needs, and reformat the data according to international standards. Our development and use of this application is the first testcase in what is intended to be an ARS-wide adoption of the platform for all the natural history collections across the Agency. Considerable progress was also made in the general upkeep and growth of the herbarium collections: 1923 incoming specimens were processed, we sent 842 specimens as exchange or gifts, added 75 new cultivar standard specimens, and mounted almost 1000 new specimens. We also continued to make strides in processing the backlog of unmounted and unlabeled material, some of which have been untouched for decades. Staff began curation of several special subsets of the collection to capture their data and prevent further degradation, including the McKay Nut Collection, the den Boer Malus Collection, and the Rogers Manihot Collection. Additionally, we hosted 113 visitors to the herbarium collections through tours and research visits.

1. Collection management of the USDA’s natural history collections for expanded access. Preserving scientific specimens and the data about them is an important means of documenting the natural world and provides a biological snapshot of a given time and place. The USDA maintains more than 200 assemblages of these specimens; one collection, the U.S. National Arboretum Herbarium, which stores 700,000 preserved plants, was recently digitized in its entirety to make the objects and associated data more available to researchers and the public. ARS scientists in Washington, D.C. have been working with software developers to create a management system for the digital assets and an innovative online collection gateway. The Herbarium is the first in what is set to be a series of USDA collections managed and presented through a single portal for the very first time, thereby increasing the reach and impact of our invaluable biological collections.